Give reasons for the following :
'Carbon-oxygen bond lengths in formic acid aer `1.23 Å` and `1.36 Å` and both carbon-oxygen bonds in sodium formate have the same value, i.e., `1.27 Å`.

Which of the following has longest C-O bond length? (Free C-O bond length in CO is 1.128Å ).

Give reasons for the following in one or two sentences ' The central carbon - carbon bond in 1,3- butadiene is shorter than that in n- butane ' .

The bond length in CO is 1.128 Å. What will be the bond length of CO in Fe(CO)_(5) ?

Give reasons for the following : (i) Though nitrogen exhibits + 5 oxidation state, it does not fonn pentahalide. (ii) Electron gain enthalpy with negative sign of fluorine is less than that of chlorine. (iii) The two oxygen-oxygen bond lengths in ozone molecule are identical.

Give reasons for the following (a) PF_(5) is know but NF_(3) is not (b) H_(2)O is a good solvent (c ) BF_(3) is non- polar but planar (e) Carbon -oxygen (C-O) bond lengths are equal in Na_(2)CO_(3) (f) MgF_(2) is more soluble in water than MgCI_(2) .

(a) Explain why cleavage of phenyl ethers with HBr always produces phenol and alkyl bromides and not bromobenzene and alkanols. (b) Give reasons for the following: (i) The dipole moment of diethyl ether (1.18D) is lower than that of water (1.84D). (ii) The C-O-C bond angle in ethers is higher than H-O-H angle in water though oxygen is sp3 hybridized in both the cases. (iii) Dimethyl ether is completely miscible with water but diethyl ether is soluble in water to a small extent.

Account for the following: (i) In reaction involving cleavage of carbon-oxygen bond of alcohols some acid is added to facilitate the reaction. (ii) The order of reactivity of halogen acids with alcohols is HI gt HBr gt HCl . (iii) Phenols do not undergo substitution at the carbon of C-OH bond.

The binary compounds of oxygen with other elements are called oxides. They are classified depending either upon their acid-base characteristics or on the basis of oxygen content. (a) Normal oxides : These oxides which contain oxygen atom as permitted by the normal oxidation number, i.e., -2 normal oxide may be acidic, basic, amphoteric or neutral. (b) Polyoxides : The oxides which contain oxygen atoms different than those permitted by the normal oxidation number of -2 . (i) Peroxides : Two oxygen atoms are linked to each other and oxyegen has -1 oxidation number. They contain (O -O)^(2-) unit. (ii) Superoxodes : These oxides contain (O-O)^(-1) unit, i.e., each O-atom has oxidation number -1//2 . (c) Suboxides : These contain low content of oxygen than expected. (d) Mixed oxides : These oxides are made of two simpler oxides. Which of the following pairs contains mixed oxides ?

The binary compounds of oxygen with other elements are called oxides. They are classified depending either upon their acid-base characteristics or on the basis of oxygen content. (a) Normal oxides : These oxides which contain oxygen atom as permitted by the normal oxidation number, i.e., -2 normal oxide may be acidic, basic, amphoteric or neutral. (b) Polyoxides : The oxides which contain oxygen atoms different than those permitted by the normal oxidation number of -2 . (i) Peroxides : Two oxygen atoms are linked to each other and oxyegen has -1 oxidation number. They contain (O -O)^(2-) unit. (ii) Superoxodes : These oxides contain (O-O)^(-1) unit, i.e., each O-atom has oxidation number -1//2 . (c) Suboxides : These contain low content of oxygen than expected. (d) Mixed oxides : These oxides are made of two simpler oxides. Which of the following oxides is paramagnetic in nature ?

The binary compounds of oxygen with other elements are called oxides. They are classified depending either upon their acid-base characteristics or on the basis of oxygen content. (a) Normal oxides : These oxides which contain oxygen atom as permitted by the normal oxidation number, i.e., -2 normal oxide may be acidic, basic, amphoteric or neutral. (b) Polyoxides : The oxides which contain oxygen atoms different than those permitted by the normal oxidation number of -2 . (i) Peroxides : Two oxygen atoms are linked to each other and oxyegen has -1 oxidation number. They contain (O -O)^(2-) unit. (ii) Superoxodes : These oxides contain (O-O)^(-1) unit, i.e., each O-atom has oxidation number -1//2 . (c) Suboxides : These contain low content of oxygen than expected. (d) Mixed oxides : These oxides are made of two simpler oxides. Which of the following pairs contains amphoteric oxides ?